Radiotherapy, also known as radiation oncology, is the medical use of ionizing radiation to destroy cancer cells in a malignant tumor. The goal of radiotherapy is to destroy as many cancer cells as possible while limiting harm to surrounding healthy tissue.
FIG. 1 shows a side view of a conventional treatment system 100. System 100 includes a gantry 102 that positions a radiation delivery apparatus 104 around a patient during radiation therapy. The patient is positioned by a treatment couch 106. The combination of gantry and couch movements provides greater flexibility in delivering the ionizing radiation to the patient.
In FIG. 1, all movements are shown at their zero positions except for the vertical displacement and the longitudinal displacement of treatment couch 106. Gantry 102 is mounted via a bearing to a stand 103 that is fixed to a floor 108. Gantry 102 can rotate radiation delivery apparatus 104 about a horizontal axis 110, thereby defining a radiation isocenter 112 where the radiation beams meet in space. Treatment couch 106 has a turntable 114 fixed to floor 108 so it can rotate isocentrically about a vertical axis 116 passing through isocenter 112. Treatment couch 106 has a couch top 118 that can rotate eccentrically relative to turntable 112 about a vertical axis 120. FIG. 2 shows a top view of treatment couch 106 with couch top 118 at the zero position of the isocentric rotation about vertical axis 116, and FIG. 3 shows a top view of treatment couch 106 with couch top 118 after an isocentric rotation about vertical axis 116. Referring back to FIG. 1, couch top 118 can also translate vertically along vertical axis 120, translate laterally in lateral directions 124, and translate longitudinally in longitudinal directions 122.
Use of the same reference numbers in different figures indicates similar or identical elements.